Piperaquine microcapsules and compositions containing them

ABSTRACT

The present invention provides a microcapsule pharmaceutical composition of at least a bisquinoline drug. said microcapsule comprises a drug core of a pharmaceutically effective amount of a bisquinoline drug and a polymeric coating over the core. This microcapsule pharmaceutical composition has desirable pharmaceutical properties, including taste masking effect and a high stability.

REFERENCE TO PRIOR APPLICATION

This application claims the benefit of International Application No.PCT/EP2014/055757 and U.S. Provisional Application No. 61/804,448, filedMar. 22, 2013, the disclosure of each of which is incorporated byreference herein in its entirety.

BACKGROUND

The most widely used dosage forms for oral administration includetablets and capsules. However, such dosage forms have severaldisadvantages. For example, it is estimated that 50% of the populationhave problems swallowing tablets. In particular, it is difficult forsome elderly persons to swallow tablets or capsules or to medicatechildren who are unable or unwilling to swallow tablets or capsules.This leads to poor or non-compliance with the treatment, and thus has anegative impact on the efficacy of the treatment. The bitter taste ofmany actives precludes the medication from being easily sprinkled ontofood, a commonly used method of administering medications to elderly andchildren.

A number of methods are known for masking the taste of drugs; tastemasking techniques may be divided into physical, chemical, biochemicaland organoleptic methods. The technique to be adopted will depend onseveral factors, but primarily on the extent of bitterness of the drugto be incorporated into an oral pharmaceutical formulation. Organolepticmethods of taste-masking involve addition of a flavoring and/orsweetening agent and as such are relatively simple. However, simpleaddition of a taste-masking agent such as a flavoring agent or sweeteneris frequently not useful by itself, unless the drug to be taste-maskedis not particularly bitter. The most common masking methods, however,are based on physical means, including agglomeration, coating, andmicroencapsulation. Microencapsulation is essentially a process by whichcoatings are applied to small particles of solids, droplets of liquidsor dispersions, so as to form microcapsules.

The taste masked formulation of bitter drug-containing cores shouldallow the complete release of the drugs in the gastrointestinal tractwithin a suitable time period. For example, bitter drug-containing coresincorporated into chewable tablets typically have thick coatings ofmostly water-insoluble polymers, to resist fracture during tabletcompression and/or during chewing and concomitant leakage of the bitteractive; however, in this case a substantially complete release of thedrug from such chewable tablets in the gastrointestinal tract may beachieved only after several hours from administration.

Among the drugs having a bitter taste there are the bisquinoline drugs.Bisquinoline derivatives are compounds with two quinoline groups boundby a covalent aliphatic or aromatic link. Several of these compoundshave been identified as antimalarian medicaments and includehydroxypiperaquine, dichlorquinazine, 1,4-bis (7-chloro-4-quinolylamino)piperazine, piperaqine. Bisquinolines includes free form of the compoundand their pharmaceutically acceptable different forms, such as salts,solvates, esters, racemic form, enantiomers, diastereomers, metabolites,prodrugs, analogues, polymorphs, hydrates, hyper-hydrate. Particularlyinteresting is piperaquine (PQ) and piperaquine tetraphosphatetetrahydrate phosphate (PQP). PQP is the bisquinoline,4,4′-(1,3-propanediyldi-4,1-piperazinediyl) bis(7-chloroquinoline)phosphate hydrate (1:4:4) or7-chloro-4-[4-[3-[4-(7-chloroquinolin-4-yl)piperazin-1-yl]propyl]piperazin-1-yl]quinolinephosphoric acid, hydrate. Its molecular formula is:C₂₉H₃₂Cl₂N₆.4(H₃PO₄).4(H₂O), MW: 999.56. The molecular structure is:

Any crystalline polymorphs and hydrates of PQ and PQP representingdifferent solid state molecular forms of the same compound can be usedin the present invention.

Formulating piperaquine or piperaquine phosphate in their differentforms is complicated by its bitter taste. Furthermore, PQP may inducechemical reactions on chemically reactive agents; instability anddecomposition or degradation of chemically sensitive active agent suchas dihydroartemisinin may occur when this agent is used in combinationwith PQP (Chem. Med. Chem., 2007, 1448-1463). Moreover, the formulationprepared with the bisquinoline drug should be controlled and customizedboth when PQP is used alone and in combination with other activeagent(s).

SUMMARY OF THE INVENTION

The present invention provides a taste-masked microcapsule compositionof a bisquinoline drug, wherein the microcapsule comprises a drug coreand a coating (layer) of a polymeric material over the core and havingthe average coating weight of said microcapsule of from about 2 to about40% weight of the total weight of the microcapsule composition.

Particularly interesting is coacervated microcapsule compositioncomprising piperaquine or piperaquine phosphate and theirpharmaceutically acceptable different forms, such as salts, solvates, orprodrugs thereof. The invention provides the pharmaceutical compositionscomprising these microcapsule compositions with suitable drug contentcombined with a taste masking effect. The pharmaceutical compositionsmay be also used to form a stable combination product (combo product) ofPQP microcapsules with at least one unstable or chemically sensitiveactive agent. Chemically sensitive or reactive agent has high chemicalreactivity, it contains reactive moiety/ies, such as for example acetalgroups, and easily undergoes degradation reactions, such as hydrolysisor dehydrogenation to form for example aldehyde/ketone and ring openingdegradation products.

The present invention also provides a process for preparing microcapsulecomposition of bisquinoline drug and the process for preparingpharmaceutical compositions comprising taste-masked microcapsule aloneor in combination with other drug. The microcapsule preparation processincludes the steps of: (a) forming a mixture comprising a bisquinolinedrug, a polymeric material, and an organic solvent, (b) inducing thephase separation of the polymeric material from the solvent onto thedrug, and (c) separating the drug microcapsule composition from theorganic solvent.

Microencapsulation of bisquinoline drug (PQ or PQP) in the differentforms is carried out to mask the bad taste, to minimize discolorationupon light exposure. The microencapsulation disclosed in the presentinvention is also effective in preventing and minimizing the degradationof further highly reactive agent induced by PQP, when both active agentand drug are formulated in a combo dosage form.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: XRPD of both PQP (top) and of PQP microcapsules of Sample 2(bottom)

FIG. 2: “In vitro” dissolution profiles of microcapsules with coatinglevel 10, 15, 20% w/w; □: Sample 1; ⋄: Sample 2; ▴: Sample 3; x: Sample4; *: Sample 5; ◯: Sample 6

FIG. 3: “In vitro” dissolution profiles of microcapsules with coatinglevel 15% w/w; ⋄: Sample 2; □: Sample 7; ▴: Sample 8

FIG. 4: “In vitro” dissolution profiles of microcapsules with coatinglevel 20% w/w; ▴: Sample 3; □: Sample 11; ▪: Sample 12; x: Sample 13

FIG. 5: “In vitro” dissolution profiles of microcapsules with 20% w/wcoating level; x: Sample 13; ◯: Sample 14; −: Sample 15; ▴: Sample 16;+: Sample 17; ⋄: Sample 18; □: Sample 19; *: Sample 21

FIG. 6: “In vitro” dissolution profiles of microcapsules with 15% w/w ofcoating level; ⋄: Sample 9; □: Sample 10; ▴: Sample 22; x: Sample 20.

In all figures the “%” represents the bisquinoline fraction releasedwith respect to the total amount.

DETAILED DESCRIPTION OF THE INVENTION

All documents cited herein are incorporated by reference for allpurposes.

As used herein, the term “microcapsules” refers to a drug core coatedwith polymeric material, that is the polymeric material forms a layeraround the drug core.

The term “coacervated microcapsules” refers to a drug core coated withpolymeric material using the coacervation method.

“Microencapsulation conducted by phase separation” and “coacervation”mean an encapsulation process in which the drug is dispersed in asolution containing a coating polymeric material, and procedures arethen followed which result in deposition of the coating on the drugcore, thus preparing “coacervated microcapsules”.

As used herein, the term “coating weight” or “coating level” refers tothe dry weight of the polymeric material divided by the weight of theentire microcapsule, multiplied by 100. For example, a coating weight of15% w/w means that for the given microcapsule, the coating constitutes15% of the weight of the microcapsule. As used herein, the term “averagecoating weight” refers to the mean value of the coating weight for apopulation of microcapsules. For example, if half of the microcapsulesin a given population have a coating weight of 10% w/w and the otherhalf has a coating weight of 20% w/w, the average coating weight for thegiven population of microcapsules is 15% w/w. All “coating weight” or“coating level” values given in the present text are “average coatingweight”.

The term “pharmaceutical formulation” as used herein refers toformulations containing the microcapsules of the invention incombination with carriers or excipients suited to a selected drugdelivery dosage form.

As used herein and unless otherwise specified, references tobisquinoline drug or piperaquine (PQ) or piperaquine phosphate (PQP)also encompasses a salt, solvate, or prodrug thereof; it is alsointended for esters, racemic form, enantiomers, diastereomers,polymorphs, hydrates, or hyper-hydrate thereof.

The present invention provides a taste-masked microcapsules compositionof bisquinoline drug, where the microcapsule consists of a drug core anda coating (also called coating layer) of a polymeric material andwherein the average coating weight of said microcapsule is from about 2to about 40% weight of the total weight of the microcapsule composition.The bisquinoline drug is selected from the group consisting of such ashydroxypiperaquine, dichlorquinazine, 1,4-bis (7-chloro-4-quinolylamino)piperazine, piperaquine, piperaquine phosphate or pharmaceuticallyacceptable different forms, such as salts, solvates, hydrates,hyper-hydrate esters, metabolites, prodrugs, analogues, racemic form,enantiomers, diastereomers polymorphs thereof.

In one embodiment of the present invention, the bisquinoline drug ispiperaquine phosphate in any pharmaceutically acceptable different form.

In one embodiment of the invention the bisquinoline is piperaquinetetraphosphate in hydrated form.

The coating of polymeric material of the present invention is depositedover the drug core thus forming an uniform layer over the core. Thepolymeric material may be any suitable, pharmaceutically acceptablepolymer that forms a coating around the drug particles, and therebyyields drug microcapsules exhibiting taste-masked properties. Examplesof polymers which may be used in the present invention are selected fromthe group consisting of ethylcellulose, polyvinyl acetate celluloseacetate, cellulose acetate butyrate, ammonium-methacrylate copolymers,cellulose acetate phthalate, cellulose acetate butyrate,polymethacrylates, hydroxypropyl methylcellulose phthalate,carboxymethyl ethylcellulose, polylactic acid and mixtures thereof. Inthe present invention the coating polymeric material is preferablyinsoluble in water.

In one embodiment, the water-insoluble polymeric material of theinvention is ethylcellulose.

The amount and type of polymeric material in the coating contributestoward regulating the release of the drug and modulating the degree oftaste masking. The average coating weight of the microcapsules of thepresent invention (also called coating level) is from about 2 to about40% weight of the total weight of the microcapsule, or from about 5 toabout 30% weight of the total weight of the microcapsule, or from about10 to about 20% weight of the total weight of the microcapsulecomposition, including about 5% w/w, about 10% w/w, about 15% w/w, about20% w/w, about 25% w/w, about 30% w/w, about 35% w/w, or about 40% w/w.The average coating weight of the microcapsules of the present inventionis preferably from about 10% w/w to about 20% w/w. The microcapsuleshave an average coating weight of preferably about 10% w/w, or about 15%w/w, or about 20% w/w.

The wettability of the water insoluble polymeric coating of themicrocapsules may be improved by treatment of the microcapsules withsurfactants.

The taste masking of the coating is effective both on dry form and aftersuspension in water (60 seconds).

The microcapsules have particles size distribution (PDS) in the rangecomprised between 180 and 400 microns, preferably between 200 and 300μm.

In one embodiment of the invention the taste-masked microcapsulecomposition consists of a drug core and a coating (layer) of acoacervated polymeric material.

In one embodiment of the invention the taste-masked microcapsulecompositions consists of piperaquine tetraphosphate tetrahydrate(PQP.4H₂O) core and a coating (layer) of coacervated ethylcellulose.

In one embodiment of the invention the microcapsules of a bisquinoline(such as piperaquine tetraphosphate tetrahydrate) may be combined withadditional active agent. The additional agent may be a drug that is notsuitable to be used in pharmaceutical formulation because of itsintrinsic chemical instability (such as agent sensitive to hydrolysis orthat may undergo various degradation pathways) and/or also incompatiblewith many substances, including bisquinoline drugs (such as PQP).

The microcapsule of bisquinoline drug (such as PQ or PQP) or any of itsforms is effective in:

-   -   masking the unpleasant taste of the drug;    -   preventing/minimizing discoloration of the drug induced by light        exposure;    -   preparing stable combination with other unstable or chemically        reactive active agents by preventing and minimizing the        degradation induced by PQP.

The characteristics of the produced microcapsules can be summarized:

-   -   optimal “in vitro” dissolution profile;    -   coating level uniform around the drug core and constant from        batch to batch;    -   drug stability upon storage;    -   drug's (PQ or PQP) physical properties such as crystalline        structure are maintained after microencapsulation process;    -   light discoloration of the drug microencapsulated equivalent to        that of starting drug;    -   particles size distribution (PDS) in the range comprised between        180 and 400 microns, preferably between 200 and 300 μm;    -   values of residual ingredients used in the preparation process        (such as cyclohexane and phase inducer agent, PSI) always low        and consistent with pharmaceutically allowable ranges.

The pharmaceutical compositions of the present invention may comprisetaste-masked microcapsule composition of a bisquinoline drug and furtherinactive excipients.

In another embodiment, the present invention provides a process formicrocapsules preparation.

The microcapsules of the present invention may be prepared by providinga homogeneous solution of a polymeric material in a suitable solvent inwhich the drug core and, optionally, coating additives are dispersed insuspension. Phase separation may then be applied to causeinsolubilization of the polymeric material, which gels (coacervates)around the drug crystals to form the microcapsules. Phase separation maybe performed, for example, through variation in temperature or in pH orby adding to the organic solvent a material promoting phase-separation(phase inducer agent) that cause the coacervation of the polymericmaterial. Finally, the microcapsules obtained are subjected tohardening, if required, and recovered.

More specifically, the microencapsulation process used for thepreparation of taste-masked microcapsules of the present inventioncomprises the following steps: (a) forming a mixture comprising abisquinoline drug, a polymeric material, and an organic solvent, (b)inducing the phase separation of the polymeric material from the solventonto the drug, and (c) separating the drug microcapsule composition fromthe organic solvent.

In one embodiment the microencapsulation process comprises: (a) forminga mixture comprising a bisquinoline drug, a polymeric material, amaterial for promoting phase separation of the polymeric material, andan organic solvent, (b) inducing phase separation of the polymericmaterial from the solvent onto the drug, and (c) separating the drugmicrocapsules from said organic solvent.

Hence, the microcapsules of the bisquinoline drug of the invention areprepared by first forming a mixture of the bisquinoline drug, apolymeric material (to serve as the coating), and a material forpromoting phase separation of the polymeric material (phase induceragent) and optionally further ingredients in an organic solvent. Mixingis preferably conducted along with stirring or agitation using anynumber of conventional means. The solvent should be one in which thepolymeric materials are soluble at higher temperatures, i.e.,temperatures generally on the order of 70° C. or higher, but insolubleat ambient temperature; also, the drug should be substantially insolublein the solvent at all temperatures used in the manufacturing process.After admixture of these initial components, the suspension so formed isheated for a time period and to a temperature sufficient to dissolve thefirst and second polymeric materials in the solvent. In addition,stirring is preferably continued at a predetermined stirring rate; asuitable stirring rate may be readily determined by one skilled in theart. The temperature is at or below the boiling point of the solvent;generally the components will be heated to a temperature of 70° C. orhigher, and preferably to a temperature of at least about 75° C.However, care must be taken not to heat to a temperature which coulddegrade the drug. Phase separation of the polymeric material from thesolvent onto the drug core is induced by cooling at appropriate rate andto appropriate temperature, thus producing a dispersion of the drugmicrocapsule (microencapsulated drug). It will be appreciated by thoseskilled in the art that the cooling rate can be varied to optimizeproperties of the microcapsules, e.g., with respect to aggregation,flowability and release profile. The solvent and phase inducer agent arethen removed by decanting, filtering or the like, followed by washingwith solvent to remove any traces of the phase inducer agent, and thendrying, again at appropriate temperature so that the drug or coatingmaterial could be adversely affected. Drying is usually although notnecessarily conducted for at least about 6 hours, and longer.

Suitable phase inducer agents which may be used in the present inventioninclude polyethylene, polyisobutylene, butyl rubber, polybutadiene,isoprene methacrylic polymers, organosilicon polymers such aspolydimethyl siloxane, paraffin, etc. In one embodiment, the phaseinducer agent is polyethylene (epolene).

The organic solvent may be a single organic solvent or it may include amixture of organic solvents. In accordance with the coacervationprocess, the organic solvent is chosen so as to dissolve the coatingpolymeric material, but not the drug and the possible coatingadditive(s) which remain dispersed in the form of solid particles insuspension. Suitable organic solvents include cyclohexane or otherhydrocarbon solvents. In one embodiment, the organic solvent iscyclohexane.

Suitable polymeric material include ethylcellulose, polyvinyl acetate,cellulose acetate, cellulose acetate butyrate, ammonium-methacrylatecopolymers, cellulose acetate phthalate, cellulose acetate butyrate,polymethacrylates, hydroxypropyl methylcellulose phthalate,carboxymethyl ethylcellulose, polylactic acid and mixtures thereof.

The optionally further ingredients may be a gastrosoluble pore former;this ingredient may be a gastrosoluble organic or inorganic pore-formersand may be selected from the group consisting of calcium carbonate,calcium phosphate, calcium saccharide, calcium succinate, calciumtartrate, ferric acetate, ferric hydroxide, ferric phosphate, magnesiumcarbonate, magnesium citrate, magnesium hydroxide, magnesium phosphateand mixtures thereof.

In one embodiment of the process for preparing taste-masked particlesaccording to the present invention, the drug is piperaquinetetraphosphate tetrahydrate, the water-insoluble polymer isethylcellulose, the phase inducer agent is polyethylene, the solvent iscyclohexane.

In one embodiment of the invention, the drug is piperaquinetetraphosphate tetrahydrate, the water-insoluble polymer isethylcellulose in amount between about 1.2 and 2% w/w, the phase induceragent is polyethylene in amount between about 0.5 and about 2% w/w, thesolvent is cyclohexane.

In one embodiment of the invention, the drug is piperaquinetetraphosphate tetrahydrate, the water-insoluble polymer isethylcellulose in amount of about 1.2% w/w, the phase inducer agent ispolyethylene in amount of about 2% w/w, the solvent is cyclohexane.

In one embodiment of the invention, the drug is piperaquinetetraphosphate tetrahydrate, the water-insoluble polymer isethylcellulose in amount of about 1.2% w/w, the phase inducer agent ispolyethylene in amount of about 0.5% w/w, the solvent is cyclohexane.

In one embodiment of the invention, the drug is piperaquinetetraphosphate tetrahydrate, the water-insoluble polymer isethylcellulose in amount of about 2% w/w, the phase inducer agent ispolyethylene in amount of about 2% w/w, the solvent is cyclohexane.

The taste-masked composition of the invention may be also prepared byother methods. Core particles comprising a bisquinoline drug may beprepared followed by coating said core particles by applying a filmforming polymer optionally in presence of other coating additives; thiscan be achieved for example by fluid bed. Said film forming polymer maybe a single polymer or may be water-insoluble polymer in mixture withfurther ingredients, such as a gastrosoluble organic or inorganicpore-formers. The water-insoluble polymer may be selected from the groupconsisting of ethylcellulose, polyvinyl acetate, cellulose acetate,cellulose acetate butyrate, methacrylate copolymers and combinationsthereof. The gastrosoluble pore former may be selected from the groupconsisting of calcium carbonate, calcium phosphate, calcium saccharide,calcium succinate, calcium tartrate, ferric acetate, ferric hydroxide,ferric phosphate, magnesium carbonate, magnesium citrate, magnesiumhydroxide, magnesium phosphate and mixtures thereof.

In another embodiment, the taste-masked drug microcapsule, optionallycombined with additional drug may be combined with inactive carrier orexcipients. Excipients for use in the compositions or dosage forms ofthe present invention include fillers, diluents, glidants,disintegrants, binders, lubricants etc. Other pharmaceuticallyacceptable excipients include acidifying agents, alkalizing agents,preservatives, antioxidants, buffering agents, chelating agents,coloring agents, complexing agents, emulsifying and/or solubilizingagents, flavors and perfumes, humectants, sweetening agents, wettingagents etc.

Examples of suitable fillers, diluents and/or binders include, but arenot limited to, lactose (e.g. spray-dried lactose, α-lactose, β-lactose,Tabletose®, various grades of Pharmatose®, Microtose® or Fast-Floc®),microcrystalline cellulose (e.g. Avicel PH101, Avicel PH102, CeolusKG-802, Ceolus KG-1000, Prosolv SMCC 50 or SMCC90, various grades ofElcema®, Vivacel®, Ming Tai® or Solka-Floc®), hydroxypropylcellulose,L-hydroxypropylcellulose (low substituted), hydroxypropylmethylcellulose (HPMC) (e.g. Methocel E, F and K, Metolose SH ofShin-Etsu, Ltd, such as, e.g., the 4,000 cps grades of Methocel E andMetolose 60 SH, the 4,000 cps grades of Methocel F and Metolose 65 SH,the 4,000, 15,000 and 100,000 cps grades of Methocel K; and the 4,000,15,000, 39,000 and 100,000 grades of Metolose 90 SH), methylcellulosepolymers (such as, e.g., Methocel A, Methocel A4C, Methocel A15C,Methocel A4M), hydroxyethylcellulose, sodium carboxymethylcellulose,carboxymethylhydroxyethylcellulose and other cellulose derivatives,sucrose, xanthan gum, cyclodextrin (e.g., gamma-cyclodextrin), agarose,sorbitol, mannitol, dextrins, maltodextrins, starches or modifiedstarches (including potato starch, maize starch and rice starch),calcium phosphate (e.g. basic calcium phosphate, calcium hydrogenphosphate, dicalcium phosphate hydrate), calcium sulfate, calciumcarbonate, sodium alginate, collagen etc. or combinations thereof.

Specific examples of diluents include. e.g. calcium carbonate, dibasiccalcium phosphate, tribasic calcium phosphate, calcium sulfate,microcrystalline cellulose, powdered cellulose, dextrans, dextrin,dextrose, fructose, kaolin, lactose, mannitol, sorbitol, starch,pregelatinized starch, sucrose, xanthan gum, gamma-cyclodextrin, etc.and combinations thereof.

Specific examples of glidants and lubricants include, e.g., stearicacid, magnesium stearate, calcium stearate or other metallic stearates,talc, waxes and glycerides, light mineral oil, PEG, glyceryl behenate,colloidal silica, hydrogenated vegetable oils, corn starch, sodiumstearyl fumarate, polyethylene glycols, alkyl sulfates, sodium benzoate,sodium acetate, etc.

Other excipients include, e.g., flavoring agents, coloring agents,taste-masking agents, pH-adjusting agents, buffering agents,preservatives, stabilizing agents, anti-oxidants, wetting agents,humidity-adjusting agents, surface-active agents, suspending agents,absorption enhancing agents, agents for modified release etc.

Non-limiting examples of flavoring agents include, e.g., cherry, orange,banana, or other acceptable fruit flavors, or mixtures of cherry,orange, and other acceptable fruit flavors, at up to, for instance,about 3% based on the tablet weight. In addition, the compositions ofthe present invention can also include one or more sweeteners such asaspartame, sucralose, or other pharmaceutically acceptable sweeteners,or mixtures of such sweeteners, at up to about 2% by weight, based onthe tablet weight. Furthermore, the compositions of the presentinvention can include one or more FD&C colorants at up to, for instance,0.5% by weight, based on the tablet weight.

Antioxidants include, e.g., ascorbic acid, ascorbyl palmitate, butylatedhydroxyanisole, butylated hydroxytoluene, hypophosphorous acid,monothioglycerol, potassium metabisulfite, propyl gallate, sodiumformaldehyde sulfoxylate, sodium metabisulfite, sodium thiosulfate,sulfur dioxide, tocopherol, tocopherol acetate, tocopherolhemisuccinate, TPGS or other tocopherol derivatives, etc.

In another embodiment, the taste-masked microcapsules composition of theinvention may be formulated into a variety of final dosage formsincluding free-flowing material, powder, granule, tablet, capsule orsachet.

Any further manipulation of the PQP microcapsule for the preparation ofa dosage form may be carried out under controlled temperature and lowmoisture conditions. This approach may be used when the formulationincludes some unstable or chemically reactive active agents. Controlledconditions that may be applied may include temperature below about 27°C. and relative humidity below about 50% RH.

Tablets may be in form of a chewable tablet or a dispersible tablet.Chewable tablets are solid dosage form containing the drug that isintended to be chewed, producing a residue in the oral cavity that iseasily swallowed; it is therefore suitable also for administration to apatient (both adult and children) who may have swallowing difficulties.Dispersible tablets are solid dosage form that can be dispersed in smallamount of liquid before administration giving a homogenous dispersion,or they can be easily dispersed directly in the mouth (orallydispersible tablets). Sachets may be prepared for permanent orextemporaneous suspensions and for direct administration in the mouth.The powder may be a fast dissolving powder that is formulated in a drysyrup for ease of swallowing; It may be administered directly in powderform, or first hydrated with a liquid, for example with 3-5 mL of waterin a tablespoon or 15-50 mL of water in a glass.

The present invention discloses a process for preparing a tabletcomprising: (a) forming a mixture comprising a bisquinoline drug, acoating polymeric material, a material for promoting phase separation ofthe polymer, and an organic solvent, (b) inducing phase separation ofthe polymeric material from the solvent onto the drug, (c) separatingthe drug microcapsules from said organic solvent, (d) mixing the drugmicrocapsules and other excipients to prepare a compressible blend, and(e) compressing said compressible blend into tablets. The process mayfurther comprise adding at least one other active agent in step (d).

The microcapsules may be granulated before mixing them with otherexcipients or before mixing with other drug (step d); or themicrocapsule may be mixed with the other active agent and then thismixture may be granulated and then mixed with other excipients. Thisgranulation step may be also applied in the preparation of dosage formsdifferent from the tablet.

The microcapsules of the invention or the final pharmaceuticalcomposition comprising the drug microcapsules may further receive one ormore further protective coating layers, such as HPMC, HPC, PVA and otherwater soluble polymers.

In another embodiment, the present invention provides a method fortreating malaria. The method comprises administering to an individual inneed thereof a pharmaceutical composition comprising taste-maskedmicrocapsules, wherein the microcapsules comprise the drug and awater-insoluble polymer coating; the composition may further comprise anadditional pharmaceutically effective agent, for exampledihydroartemisinin. The dose of the microencapsulated drug alone or incombination with an additional pharmaceutically effective agent to beadministered to an individual may vary depending on the age of theindividual being treated as well as the indication. The followingexamples are provided for purposes of illustration, and should in no waybe construed to limit the present invention.

EXPERIMENTAL 1. Methods for Characterization

Particle size distribution (PSD): an amount of microcapsules in therange of 25-50 g of microcapsules is poured into a 100 mL HDPE bottle,0.2% (w/w) of Syloid 244 (colloidal silicon dioxide, WR Grace, Columbia,Md.) and manually blended for 2 minutes; the mixture of microcapsulesand Syloid 244 is sieved then with a digital Octagon apparatus for 10minutes at amplitude 7.

Bulk density and tapped density of powders is measured according toMethod USP 34 <616>.

Dissolution profile: Ph Eur [2.9.3]; apparatus n° 2; dissolution medium:gastric simulated fluid pH 1.2 0.5% of Tween 80 without pepsin;dissolution medium volume: 900 mL; dissolution medium temperature:37±0.5° C.; withdrawal at: 5, 15, 30, 60 and 120 min.

Water content: Karl Fischer titration: Ph. Eur. 2.5.12 Method; followingsample titration conditions are applied: sample solvent: methanol:formamide 1:1; sample weight: 50 mg; the value of water content in asample is expressed as % w/w.

Residual cyclohexane: gas-chromatography (head space analysis).

Photostability Testing: ICH conditions “Q1B: Photostability (Option 1)”.

X-Ray Powder Diffraction (XRPD) measurements are performed on a PhilipsX′Pert PRO diffractometer (Bragg-Brentano geometry).

IR identity.

2. Piperaquine Microcapsules Prepared at Lab Scale

2.1. Method of Preparation

Cyclohexane is poured into the microencapsulation reactor. Then, undercontinuous stirring, piperaquine tetraphosphate tetrahydrate (PQP.4H₂O),ethylcellulose and polyethylene (epolene) are added. The mixture isheated and cooled down, microcapsules recovered, and then washed (one ormore times), filtered, and dried overnight under static condition in anoven at about 40° C. The powder is sieved through a 500 μm openingstainless steel sieve.

TABLE 1 The Process flow sheet COMPONENTS STEPS EQUIPMENTS PiperaquineCOACERVATION/PHASE Reactor Ethylcellulose SEPARATION ThermocryostateEpolene¹ Stirrer Cyclohexane² WASHING Filtering system FILTERINGFiltering system DRYING Hood, Oven SIEVING Sieve ¹Removed during washingstep; ²Removed during drying step

Different samples are prepared by using different amount of polymerranging from 1.2 to 2% w/w (wherein 2% w/w means 20 g of ethylcellulosefor 1 kg cyclohexane); different amount of epolene ranging from 0.5 to2% w/w (wherein 2% w/w means 20 g of epolene for 1 kg cyclohexane);different samples of microcapsules with different amount of theethylcellulose coating (coating level % w/w, where % w/w is thepercentage of the polymer on the whole microcapsule weight) areprepared. The samples prepared are summarized in Table 2. Lab scalereactor (1 kg solvent) and industrial scale reactor (3 kg solvent) areused for the different preparations.

TABLE 2 Samples of piperaquine microcapsules Coating EthylcelluloseEpolene Cyclohexane level Sample % w/w % w/w kg Rpm % w/w 1 1.2 2 1 30010 2 1.2 2 1 300 15 3 1.2 2 1 300 20 4 1.2 0.5 1 300 10 5 1.2 0.5 1 30015 6 1.2 0.5 1 300 20 7 1.2 2 3 200 15 8, 9, 10 2 2 3 200 15 11  2 2 3200 20 12  2 2 3 220 20 13, 14, 15, 16, 2 2 3 150 20 17, 18, 19 20  2 23 160 15

The microcapsules are characterized by appearance, particle sizedistribution, residual solvent content and dissolution rate. Microscopicevaluation at the end of the microencapsulation process of the samplesshowed appropriate uniform polymer coating deposition around thepiperaquine particles consistent with the amount of the polymer used.

The amount of residual solvent (cyclohexane) is always below 100 ppm forall preparation of microcapsules prepared.

2.2. Compatibility of Piperaquine with the Coacervation ProcessConditions

A compatibility study is carried out on piperaquine to assess thecompatibility of the drug with the coacervation process. In particular,piperaquine undergoes heating/cooling cycles mimicking thermalexcursions of the process. Then, the following tests are performed bothbefore and after thermal cycles to ascertain the stability ofpiperaquine: water content analysis (Karl Fisher test); effect ofmechanical stress; crystalline structure by XRPD. The results aresummarized in the following Table 3.

PQP•4H₂O before thermal PQP•4H₂O after Test cycle thermal cycle Assay(%) 99.9 99.9 (PQP•4H₂O) Water content (%) 8.9 8.5

The crystalline structure of piperaquine and that of the microcapsulesof the Sample 2 are measured by XRPD and compared (FIG. 1): the processdoes not affect the crystalline structure of the PQP.4H₂O, since nochange in the crystalline structure is recorded. The analysis confirmsthat the PQP.4H₂O is not affected by heating/cooling cycle.

2.3. Particle Size Distribution

The PSD for the different samples is measured and reported in Table 4;all the samples match the 180-400 μm range. It is clear that the changeof the coating level and the application of different process conditionsdo not significantly affect the PSD of the microcapsules.

TABLE 4 Particle size distribution of microcapsules with coating level(C.L.) 10, 15, 20% w/w Ethylcellulose Ethylcellulose 1.2%/Epolene 2%1.2%/Epolene 0.5% C.L. 10% C.L. 15% C.L. 20% C.L. 10% C.L. 15% C.L. 20%Sieve (μm) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6  >5000.4 1.5 0.5 0.6 1.0 1.5 >425 — 3.5 2.9 — 4.0 4.0 >355 9.9 9.7 9.6 10.78.0 10.4 >250 34.8 37.0 41.1 18.0 39.8 33.7 >180 39.3 39.3 37.8 27.338.8 37.1 >125 14.8 8.2 6.7 34.1 8.5 10.9 <125 0.8 0.8 1.4 9.3 0.0 2.5125-425 — 94.2 95.2 — 95.1 92.1 125-355 98.8 — — 90.1 — —

PSD is measured on microcapsules with 15% w/w coating level produced atdifferent scale and processing conditions (Table 5); Sample 8 ismeasured on 3 replicates thus showing that the reproducibility of theprocess is high.

TABLE 5 PSD of microcapsules with coating level 15% w/w PDS % fraction(w/w) (sieves) Sample 8 Sieve μm Sample 2 Sample 7 (n = 3) SD >500 1.51.5 0.5 0.12 >425 3.5 2.5 4.1 0.46 >355 9.7 10.5 13.9 1.10 >250 37.056.0 43.9 0.58 >180 39.3 27.5 26.4 0.72 >125 8.2 2.0 9.3 0.46 <125 0.80.0 1.9 0.42

As shown in Table 6 the PSD is within the 180-400 μm range for all thebatches manufactured at large scale and having coating level 20% w/w.

TABLE 6 PSD of microcapsules with coating level 20% w/w PSD (sieves) %fraction (w/w) Sieve μm Sample 3 Sample 11 Sample 12 Sample 13 >500 0.50.8 0.0 0.0 >425 2.9 1.6 0.8 3.2 >355 9.6 6.5 5.2 23.2 >250 41.1 20.126.4 52.4 >180 37.8 26.6 42.8 18.8 >125 6.7 25.8 21.6 2.0 <125 1.4 18.43.2 0.4

2.4. Photostability Test

Piperaquine microcapsules are tested for their photostability; thetested samples have coating level 10% and 20% w/w and are prepared bothwith ethylcellulose 1.2% w/w and epolene 2.0% w/w and withethylcellulose 1.2% w/wand epolene 0.5% w/w. The test is carried out bycomparing the microcapsules versus the piperaquine alone. The samples donot show differences in discoloration upon light exposure.

2.5. Dissolution, Assay and Water Content of Microcapsules

The results of the “in vitro” dissolution test (DRT) of microcapsulesare summarized in Table 7 and presented as a graph in FIG. 2.

TABLE 7 Analysis of microcapsules with coating level 10, 15, 20% w/wEthylcellulose 1.2%/Epolene 2% Ethylcellulose 1.2%/Epolene 0.5% 1 kgCyclohexane, HC 300 rpm 1 kg Cyclohexane, HC 300 rpm C.L. 10% C.L. 15%C.L. 20% C.L. 10% C.L. 15% C.L. 20% Sample 1 Sample 2 Sample 3 Sample 4Sample 5 Sample 6 DRT (min) % SD % SD % SD % SD % SD % SD  5 47 4 30 115 1 31 3 20 1 14 0 15 93 2 77 3 39 1 75 3 53 1 37 0 30 100 1 97 2 66 193 2 82 1 58 1 60 100 1 100 1 91 3 96 2 96 2 79 1 120  — — — — 96 3 — —— — 89 1 Assay (%) 100.2 100.4 100.7 100.6 100.4 101.3 (PQP•4H₂O) Watercontent 7.6 7.3 7.2 7.7 7.2 7.1 (%)

By analyzing the data there is a clear evidence of the high coatingefficiency of the coacervation system applied. With regards to KarlFischer data, it is observed that the loss of water is very limited(above 7% referred to the drug only and not to the microcapsules); thisbehavior is important because it shows that no change in crystallinestructure occurs during processing. In fact, when an excessive waterloss occurs than this may induce a change of the crystalline structureof the drug, i.e. from crystalline to amorphous.

Table 8 and FIG. 3 show that the 15% coating level microcapsulesproduced at different scale and different processing condition behavessimilarly in term of DRT, PSD, coating efficiency. The level ofreproducibility is high.

TABLE 8 Analysis of microcapsules with coating level of 15% w/w Coatinglevel 15% EC 1.2% EC 2% EP EP 2% 2% Sample 2 Sample 7 Sample 8 1 kg 3 kg3 kg DRT (min) (n = 3) % SD % SD % SD  5 30 1 31 1 33 1 15 77 3 76 1 752 30 97 2 96 1 94 3 60 100 1 98 1 97 3 Assay (%) 100.4 100.2 100.3(PQP•4H₂O) Water content (%) 7.3 7.0 7.4 Cyclohexane (ppm) NA NA 18

Dissolution data and profile shown in Table 9 and FIG. 4 refers to themicrocapsules with coating level 20% w/w produced by scaling up theprocess.

TABLE 9 Analysis of microcapsules with coating level 20% w/w Coatinglevel 20% w/w EC 1.2% EP 2% EC 2%/EP 2% Sample 3 Sample 11 Sample 12Sample 13 1 kg 3 kg 3 kg 3 kg DRT 300 rpm 200 rpm 200 rpm 150 rpm (min)(n = 3) % SD % SD % SD % SD  5 15 1 21 1 20 1 19 1 15 39 1 53 1 51 3 460 30 66 1 79 1 79 2 75 1 60 91 3 93 2 94 1 94 2 120  96 3 94 2 95 1 96 2Assay (%) 100.7 101.1 101.0 100.4 (PQP•4H₂O) Water content 7.2 6.4 6.46.4 (%)

Table 10 and FIG. 5 show the results of the characterization ofsub-batches with coating level 20% w/w regarding the dissolutionprofile, the PSD and the assay and the results of “in vitro” dissolutionprofile, assay, PSD KF analysis, residual cyclohexane and residualepolene for final mixture (Sample 21=Sample 13+Sample 14+Sample15+Sample 16+Sample 17+Sample 18+Sample 19).

TABLE 10 Analysis of microcapsules with 20% w/w coating level EC 2%/EP2% - 150 rpm - 3 kg Reactor DRT Sample Sample Sample Sample SampleSample Sample Sample (min) 13 14 15 16 17 18 19 21 n = 6 (n = 3) % SD %SD % SD % SD % SD % SD % SD % SD   5 19 1 17 1 19 1 16 1 19 1 18 1 20 119 1  15 46 0 40 1 45 2 41 2 47 1 44 2 49 1 47 2  30 75 1 66 1 74 2 69 175 1 72 3 77 2 75 2  60 94 2 89 1 93 2 92 0 93 1 93 3 95 1 94 2  120 962 95 1 95 2 94 1 94 2 95 2 96 2 96 1 Assay 100.4 NA NA NA NA NA NA 100.0(%) (PQP•4H₂O) Water 6.4 NA NA NA NA NA NA 6.2 content (%) Epolene NA NANA NA NA NA NA 0.3 (% w/w) Cyclo- NA NA NA NA NA NA NA 45 hexane (ppm)Sieve μm PSD fraction (% w/w) >500 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 >4253.2 2.5 4.8 4.4 3.3 3.5 2.1 4.4 >355 23.2 19.2 17.0 25.6 22.3 21.1 19.518.4 >250 52.4 48.1 52.2 46.8 50.5 44.8 46.4 52.0 >180 18.8 24.1 19.517.8 16.3 20.1 21.9 20.0 >125 2.0 5.1 4.7 4.5 6.0 8.6 9.3 4.0 <125 0.4 11.8 0.9 1.6 2 0.8 1.0 125-425 96.4 96.5 93.4 94.7 95.1 94.6 97.1 94.4Bulk NA NA NA NA NA NA NA 0.58-0.63 density- Tapped density (g/mL)

Table 11 and FIG. 6 show the results of in-vitro dissolution of themanufactured sub-batches with coating level 15% w/w.

TABLE 11 Analysis of microcapsules with 15% w/w of coating level (Sample22 = Sample 9 + Sample 10) Coating Level 15% EC 2% EP 2% EC 2% EP 3 kgsolvent 2% 2 kg Sample 22 solvent Sample 9 Sample 10 n = 6 Sample 20 DRT(min) (n = 3) % SD % SD % SD % SD  5 39 2 36 2 38 1 30 1 15 79 2 77 0 801 65 2 30 94 1 95 1 95 1 88 1 60 97 1 97 1 96 1 97 1 Theoretical assay850.0 mg/g (PQP•4H₂O) Assay (%) (PQP•4H₂O) NA NA 100.6 100.4 Watercontent NA NA 7.0 6.3 (%) Epolene (% w/w) NA NA 0.3 NA Cyclohexane (ppm)NA NA 50 40 PSD (sieve) PDS fraction (% w/w) >500 μm 0.3 0.6 0.70.9 >425 μm 3.7 3.9 3.9 4.6 >355 μm 13.1 13.5 13.4 14.5 >250 μm 45.345.9 44.8 47.7 >180 μm 27.7 26.9 26.7 25.7 >125 μm 8.5 8.0 8.8 6.3 <125μm 1.4 1.2 1.7 0.3 125-425 μm   94.6 94.3 93.7 94.2

3. Piperaquine Microcapsules Prepared at Industrial Scale

3.1. Method of Preparation

Piperaquine tetraphosphate tetrahydrate, excipients and cyclohexane areplaced into the 80 gallons reactor. The reactor paddle speed is set andthe thermal cycle of microencapsulation begins; the temperatureparameters of the cycle are set (maximum heating temperature 80° C.).Drugs, polymeric material, phase separation inducing agent and solventare loaded in amount as reported in Table 12.

TABLE 12 Components of microcapsules Material Concentration ComponentsAmount (kg) (% w/w) PQP•4H₂O 20.0 7.2 Ethylcellulose 5.0 1.8Polyethylene 5.0 1.8 Cyclohexane 248.0 89.2 Total 278.0 100.0

At the end of the thermal cycle. the paddle rotation is stopped and theproduct settled down. The supernatant (solvent and polyethyleneexcipient) is removed using a pump and fresh solvent is added (about 120kg). The agitation is restarted for short period of time and then themicrocapsules are filtered under vacuum in a fluid bed equipped with a70 μm stainless steel sieve on the bottom. The whole process and thefiltration as well is carried out in inert nitrogen atmosphere. Afterthe solvent removal by filtration, the microcapsules are dried up to thelevel of the residual cyclohexane of below 3880 ppm. The obtainedproduct is discharged and sieved trough a 600 μm stainless steel sieve.

A set of coacervation processes are performed (Table 13), wherein adifferent stirrer speed is applied: about 100 rpm (Sample 23, Sample 24,Sample 25) and or about 65-70 rpm (Sample 26, Sample 27, Sample 28,Sample 29).

TABLE 13 Coacervation process conditions Sample Sample Sample SampleSample Sample Sample Microcapsule batch 23 24 25 26 27 28 29 Cyclohexane248.0 NA 248.0 248.0 248.0 248.0 NA fresh/distilled (kg) Cyclohexane NA128.8 NA NA NA NA 136.0 media (kg) Cyclohexane NA 119.2 NA NA NA NA112.0 filtered (kg) PQP•4H₂O (kg) 20.0 20.0 20.0 20.0 20.0 20.0 20.0Ethylcellulose (kg) 5.00 5.00 5.00 5.00 5.00 5.00 5.00 Epolene (kg) 5.001.50 5.00 5.00 5.00 5.00 1.20

Table 14 reports the compositions and the process parameters used forthe preparation of the large scale batches. All the batches are producedapplying a coating level of ethylcellulose equal to 20% w/w.

TABLE 14 Large scale microcapsule batches: composition and processparameters Microcapsule batch Sample 30 Sample 31 Sample 32 Sample 33Sample 34 Sample 35 Cyclohexane 248.0 NA 248.0 NA NA NA fresh/distilled(kg) Cyclohexane NA 142 NA 248 248 248 media (kg) Cyclohexane NA 106 NAfiltered (kg) PQP•4H₂O (kg) 20.0 20.0 20.0 20.0 20.0 20.0 Ethylcellulose(kg) 5.00 5.00 5.00 5.00 5.00 5.00 Epolene (kg) 5.00 1.20 5.00 1.20 1.201.20 Sedimentation 5 5 5 5 5 5 Time (min) Supernatant 136.0 136.0 136.0136.0 136.0 136.0 removed (kg) Fresh cyclohexane 120 120 120 120 120 120for filtration (kg) Filtration time (min) 7 7 7 7 7 7 Paddle 65-70 65-7065-70 65-70 65-70 65-70 (rpm)

The batches are then mixed in a 120 L bin for 15 minutes at 10 rpm.Table 15 reports the composition of the microcapsules mixtures.

TABLE 15 Composition of microcapsules mixtures Final mix Sample 30Sample 31 Sample 32 Sample 33 Sample 34 Sample 35 Total batch (kg) (kg)(kg) (kg) (kg) (kg) (kg) Sample 36 23.1 23.3 — — — — 46.4 (kg) Sample 37— — 23.7 23.3 — — 47.0 (kg) Sample 38 — — — — 23.2 23.2 46.4 (kg)

3.2. Particle Size Distribution of Microcapsules Prepared at IndustrialScale

Analysis is performed on 25 g up to 50 g on stainless steel sieves.Table 16 and 17 report the results for the different batches.

TABLE 16 Particle size distribution Sam- Sam- Sam- Sam- ple Sample pleSample ple Sample ple PSD 23 24 25 26 27 28 29 >500 μm 0.4 2.2 1.3 1.25.3 3.4 1.2 >425 μm 4.2 1.6 2.3 1.6 4.8 1.5 1.4 >355 μm 16.9 4.4 5.0 7.48.5 5.4 4.4 >250 μm 50.4 19.0 17.2 22.6 28.7 25.2 39.7 >180 μm 19.4 38.330.6 36.0 34.1 39 36.7 >125 μm 5.4 27.2 32.3 25.6 15.7 20.9 14.6 <125 μm3.3 7.3 11.3 5.6 2.9 4.6 2 125-425 μm   92.1 88.9 85.1 91.6 91.8 90.595.4

TABLE 17 Particle size distribution Sample Sample Sample Sample SampleSample PSD 30 31 32 33 34 35 >500 μm 3 3 1 1 1 1 >425 μm 3 3 1 1 11 >355 μm 7 7 17 18 11 13 >250 μm 36 31 27 25 24 21 >180 μm 35 37 41 4450 47 >125 μm 13 16 12 7 11 13 <125 μm 2 3 1 4 2 3 125-425 μm 94 94 9895 97 95

3.3. Characterization of Microcapsules Prepared at Industrial Scale

Different tests have been carried out in order to characterize ofmicrocapsules. Tables 18 and 19 report the results.

TABLE 18 Analysis of piperaquine microcapsules (industrial scale)Microcapsule batch Sample Sample Sample Sample Sample Sample Sample Time23 24 25 26 27 28 29 (min) % SD % SD % SD % SD % SD % SD % SD DRT in 519 0.9 37 0.5 31 0.5 23 0.5 26 0.5 23 1.0 22 1.5 buffer: pH 15 49 0.8 812.1 71 4.2 56 0.8 64 0.8 57 1.2 54 2.6 1.2 GF + 30 77 1.2 98 1.4 91 1.583 0.8 90 0.5 85 1.6 84 1.2 0.5% of 60 94 1.6 99 1.3 98 1.6 96 0.8 970.5 96 1.3 96 0.6 Tween 80, 120 97 1.5 99 1.2 98 1.6 98 1.0 97 0.4 971.6 97 0.6 900 ml; paddle: 50 rpm; 37.0 ± 0.5° C. Theoretical assay 800mg/g (PQP•4H₂O Assay (%) 100.8 100.5 100.5 100.2 99.8 99.9 99.4(PQP•4H₂O) Water content (%) 5.1 5.5 5.7 5.6 5.0 5.6 5.7 Residual 14981946 1095 598 1297 1107 1656 cyclohexane (ppm) (spec ≦3880 ppm) Residualepolene (% 0.3 0.1 0.4 0.9 0.7 0.3 0.6 w/w) (spec ≦1.5%) Bulk density(g/mL) 0.56 nd nd nd nd nd nd Tapped density 0.60 nd nd nd nd nd nd(g/mL) Process yield (%) 75 89 90 93 93 93 94

TABLE 19 Analysis of piperaquine microcapsules (industrial scale)Microcapsule batch Specs Sample Sample Sample Sample Sample Sample Time(reference 30 31 32 33 34 35 (min) value) % SD % SD % SD % SD % SD % SDDRT in 5 — 23 0.4 28 1.2 26 1.1 31 1.6 30 2.6 36 1.6 buffer: pH 15 560.8 65 1.6 64 1.6 73 1.4 68 2.3 78 1.8 1.2 GF + 30 83 0.4 89 0.9 90 1.594 0.8 91 1.4 95 1.0 0.5% of 60  ≧70% 97 0.0 97 0.8 98 1.5 97 1.2 96 1.597 0.4 Tween 80, 120 — 98 0.5 97 0.5 98 1.5 97 1.2 96 1.0 97 0.5 900 ml;paddle: 50 rpm; 37.0 ± 0.5° C. Assay % 70-78% 74 75 nd nd nd nd (PQP)Water content (%) — 5.9 6.2 nd nd nd nd Residual ≦3380 ppm 1385 25082009 1210 1658 1806 cyclohexane (ppm) Residual epolene ≦1.5% 0.7 0.9 0.60.2 0.5 0.3 (% w/w/) Process yield (%) 92 93 95 93 93 93

4. Piperaquine Microcapsules Prepared at Industrial Scale forRegistration Purposes (Sample 36, Sample 37) and for Clinical Trials(Sample 38)

4.1. Method of Preparation

Piperaquine tetraphosphate tetrahydrate, excipients and cyclohexane areplaced into the 80 gallons reactor. The reactor paddle speed is set andthe thermal cycle of microencapsulation begins; the temperatureparameters of the cycle are set (maximum heating temperature 80° C.).Drugs, polymeric material, phase separation inducing agent and solventare loaded in amount as reported in Table 20.

TABLE 20 Components of microcapsules Material Concentration ComponentsAmount (kg) (% w/w) PQP•4H₂O 20 7.2 Ethylcellulose 5 1.8 Polyethylene 51.8 Cyclohexane 248 89.2 Total 278 100.0

At the end of the thermal cycle, the paddle rotation is stopped and theproduct settled down. The supernatant (solvent and polyethylene) isremoved using a pump and fresh solvent is added (about 120 kg). Theagitation is restarted for short period of time and then themicrocapsules are filtered under vacuum in a fluid bed equipped with a70 μm stainless steel sieve on the bottom. The whole process, and thefiltration as well, is carried out in inert nitrogen atmosphere. Afterthe solvent removal by filtration, the microcapsules are dried up toremove residual cyclohexane. The obtained product is discharged andsieved trough a 600 μm stainless steel sieve.

Coacervation process conditions are reported in Table 21.

TABLE 21 Coacervation process conditions Sample 36 Sample 37 Sample 38Drying (min) 60 60 60 60 63 60 Stirrer speed 70 70 70 70 70 70 (rpm)Cyclohexane 310 0 0 0 310 0 (fresh/distilled) (litres) Cyclohexane 0 310310 310 0 310 media and filtered (litres) Cyclohexane for 150 150 150150 150 150 washing step (litres) PQP•4H₂O (kg) 20 20 20 20 20 20Ethylcellulose 5 5 5 5 5 5 (kg) Epolene (kg) 5 1.2 1.2 1.2 5 1.2

All the batches are produced by applying a coating level ofethylcellulose equal to 20% w/w.

4.2. Stability Testing of Batches Prepared for Registration and ClinicalTrials

Sample 36, Sample 37, Sample 38 are packaged in double polyethylene bag(inner transparent bag, outer black bag). Stability of these batches hasbeen evaluated at accelerated conditions (40° C./75% RH) for a period of6 months, as well as at long-term stability conditions (25° C./60% RH)for a period of 12 months. Results shows that these samples are stableat all conditions tested (Tables 22-27). The assay, dissolution (DRT),residual water content (%) at all stability conditions are alsocomparable to the initial values of piperaquine microcapsules. Not morethan 5% w/w of total related substances (decomposed PQP) are formed uponstorage for 6 months at 40° C./75% RH for 6 months or at 25° C./60% RHfor 12 months.

TABLE 22 Stability data for PQP microcapsules of Sample 36, conditions:25° C. at 60% relative humidity Test Specs Time: 0 time: 3 mo time: 6 motime: 9 mo time: 12 mo Assay (%) 70-78%  74 74 74 73 74 (PQP) Assay (%)95-105% NA 100 100 99 100 (PQP) with respect to time: 0 Dissolution(min) (n = 6) % DS % DS % DS % DS % DS 5 — 31 2.1 30 1.5 29 0.8 28 1.027 0.8 15 — 69 1.2 70 1.5 68 1.2 68 1.3 65 1.0 30 — 92 0.8 92 0.8 92 0.092 0.5 90 2.3 60 ≧70% 98 0.5 97 0.4 98 0.5 98 0.0 97 0.8 120 — 98 0.5 970.4 98 0.4 98 0.4 98 1.0 Water — 6.1 6.3 6.4 6.7 6.9 content (%)

TABLE 23 Stability data for piperaquine microcapsules of Sample 36,conditions: 40° C. at 75% relative humidity Test Specs Time: 0 time: 3mo time: 6 mo Assay (%) 70-78%  74 74 74 (PQP) Assay (%) 95-105% NA 100100 (PQP) with respect to time: 0 Dissolution (min) n = 6) % DS % DS %DS 5 — 31 2.1 28 1.0 29 1.3 15 — 69 1.2 68 1.5 69 2.4 30 — 92 0.8 91 1.092 0.4 60 ≧70% 98 0.5 97 0.5 98 0.4 120 — 98 0.5 98 0.5 98 0.4 Water —6.1 6.4 6.6 content (%)

TABLE 24 Stability data for piperaquine microcapsules of Sample 37,conditions: 25° C. at 60% relative humidity Test Specs Time. 0 time: 3mo time: 6 mo time: 9 mo time: 12 mo Assay (%) 70%-78% 74 74 73 73 73(PQP) Assay (%)   95-105% NA 100 99 99 99 (PQP) with respect to time = 0Dissolution (min) (n = 6) % DS % DS % DS % DS % DS 5 — 33 1.5 32 1.5 331.2 33 0.8 30 1.2 15 — 72 1.0 72 2.3 75 1.8 74 0.5 70 1.6 30 — 93 0.5 930.9 94 0.8 94 0.8 93 0.4 60 ≧70% 97 0.8 97 0.5 98 1.0 98 0.5 98 0.0 120— 97 0.8 98 0.5 98 0.6 97 0.8 98 0.4 Water — 5.9 6.4 6.4 7.0 6.9 content(%)

TABLE 25 Stability data for piperaquine microcapsules batch Sample 37,conditions: 40° C. at 75% relative humidity Test Specs Time: 0 time: 3mo time: 6 mo Assay (%) 70-78%  74 74 73 (PQP) Assay (%) 95-105% NA 10099 (PQP) with respect to time: 0 Dissolution (min) (n = 6) % DS % DS %DS 5 — 33 1.5 34 0.5 33 1.0 15 — 72 1.0 74 1.7 75 0.6 30 — 93 0.5 94 0.594 0.4 60 ≧70% 97 0.8 97 0.8 97 0.0 120 — 97 0.8 97 0.4 97 0.0 Water —5.9 6.3 6.4 content (%)

TABLE 26 Stability data for piperaquine microcapsules of Sample 38,conditions: 25° C. at 60% relative humidity Test Specs Time: 0 time: 3mo time: 6 mo time: 9 mo time: 12 mo Assay (%) 70-78%  74 73 74 74 73(PQP) Assay (%) 95-105% NA 99 100 100 99 (PQP) with respect to time: 0Dissolution (min) (n = 6) % DS % DS % DS % DS % DS 5 — 25 0.9 26 0.8 251.0 26 0.4 27 0.8 15 — 59 1.1 61 1.0 60 1.5 61 1.3 64 1.3 30 — 86 0.5 880.8 86 1.5 87 1.0 89 0.6 60 ≧70% 97 0.8 98 0.5 97 0.8 96 0.8 98 0.4 120— 98 1.0 98 0.5 98 0.4 97 0.5 99 0.5 Water — 5.9 6.4 6.8 6.9 7.4 content(%)

TABLE 27 Stability data for piperaquine microcapsules of Sample 38,conditions: 40° C. at 75% relative humidity Test Specs time: 0 time: 3mo time: 6 mo Assay (%) 70-78%  74 73 74 (PQP) Assay (%) 95-105% NA 99100 (PQP) with respect to time: 0 Dissolution (min) (n = 6) % DS % DS %DS 5 25 0.9 26 0.8 26 1.2 15 59 1.1 60 0.8 61 0.8 30 86 0.5 87 1.0 870.8 60 ≧70% 97 0.8 97 1.3 97 0.0 120 — 98 1.0 98 1.0 98 0.4 Water — 5.96.8 6.9 content (%)

The invention claimed is:
 1. A taste-masked microcapsule pharmaceuticalcomposition of a bisquinoline drug, wherein the microcapsule comprises adrug core of a pharmaceutically effective amount of a bisquinoline drugand a coating over the core of a polymeric material, and having anaverage weight of the coating of said microcapsule of from about 2 toabout 40% weight of the total weight of the microcapsule composition,wherein at least about 58% of the bisquinoline drug is released from themicrocapsule composition within about 30 minutes when tested using thePh. Eur. [2.9.3] dissolution test.
 2. The composition of claim 1,wherein the bisquinoline is selected from the group consisting ofhydroxypiperaquine, dichlorquinazine, 1,4-bis (7-chloro-4-quinolylamino)piperazine, and piperaquine, or a salt, solvate, or prodrug thereof. 3.The composition of claim 2, wherein the bisquinoline is piperaquinetetraphosphate tetrahydrate.
 4. The composition of claim 1, wherein thepolymeric material is selected from the group consisting ofethylcellulose, polyvinyl acetate, cellulose acetate, cellulose acetatebutyrate, ammonium-methacrylate copolymers, cellulose acetate phthalate,cellulose acetate butyrate, polymethacrylates, hydroxypropylmethylcellulose phthalate, carboxymethyl ethylcellulose, polylactic acidand mixtures thereof.
 5. The composition of claim 1, wherein thepolymeric material is water insoluble.
 6. The composition of claim 1,wherein the coating is deposited by coacervation.
 7. The composition ofclaim 1, wherein the polymeric material is ethylcellulose.
 8. Thecomposition of claim 1, wherein the average weight of the coating ofsaid microcapsule is from about 5 to about 30% weight of the totalweight of the microcapsule composition.
 9. The composition of claim 1,wherein the average weight of the coating of said microcapsule is fromabout 10 to about 20% weight of the total weight of the microcapsulecomposition.
 10. The composition of claim 1, in combination with anotheractive agent.
 11. The composition of claim 10, wherein the other activeagent is chemically sensitive.
 12. The composition of claim 1, in a formof a free-flowing material, of a powder, tablet, capsule or sachet. 13.The composition of claim 12, wherein the tablet is chewable or orallydispersible tablet.
 14. A process for preparing the composition of claim1, comprising: (a) forming a mixture comprising a drug core of apharmaceutically effective amount of a bisquinoline drug, a polymericmaterial, and an organic solvent, (b) inducing the phase separation ofthe polymeric material from the solvent onto the drug, and (c)separating the composition from the organic solvent.
 15. The process ofclaim 14, wherein step (a) further comprises a material for promotingphase separation of the polymeric material.
 16. The process of claim 14or 15, wherein the polymeric material is selected from the groupconsisting of ethylcellulose, polyvinyl acetate, cellulose acetate,cellulose acetate butyrate, ammonium-methacrylate copolymers, celluloseacetate phthalate, cellulose acetate butyrate, polymethacrylates,hydroxypropyl methylcellulose phthalate, carboxymethyl ethylcellulose,polylactic acid and mixtures thereof.
 17. The process of claim 16,wherein the polymeric material is ethylcellulose.
 18. The process ofclaim 15, wherein material for promoting phase separation is selectedfrom the group consisting of polyethylene, polyisobutylene, butylrubber, polybutadiene, organosilicon polymer, and paraffin.
 19. Theprocess of claim 18, wherein the material is polyethylene.
 20. Theprocess of claim 14, wherein the bisquinoline drug is piperaquinetetraphosphate tetrahydrate.
 21. The process of claim 14, furthercomprising steps: (d) mixing the separated composition and at least oneother excipient to prepare a compressible blend and (e) compressing saidcompressible blend into tablets.
 22. The process of claim 21, whereinthe polymeric material is ethylcellulose.
 23. The process of claim 21 or22 further comprising adding in step (d) at least one other chemicallysensitive active agent.
 24. The composition of claim 1, wherein at leastabout 82% of the bisquinoline drug is released from the microcapsulecomposition within about 30 minutes when tested using the Ph. Eur.[2.9.3] dissolution test.
 25. The composition of claim 1, wherein atleast about 93% of the bisquinoline drug is released from themicrocapsule composition within about 30 minutes when tested using thePh. Eur. [2.9.3] dissolution test.
 26. The composition of claim 1,wherein about 100% of the bisquinoline drug is released from themicrocapsule composition within about 30 minutes when tested using thePh. Eur. [2.9.3] dissolution test.
 27. The composition of claim 1,wherein the average weight of the coating of said microcapsule is fromabout 5 to about 30% weight of the total weight of the microcapsulecomposition.
 28. The composition of claim 1, wherein the average weightof the coating of said microcapsule is from about 10 to about 20% weightof the total weight of the microcapsule composition.